Download Ch. 12 notesf Cell cycle applies to eukaryotes structure of genetic

Ch. 12 notesf
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Cell cycle applies to eukaryotes
structure of genetic material changes when cells divide
meiosis part of sexual reproduction
all cells are produced by cell division
all cells don’ t divide
cell division is part of the life of every cell
growth and repair and reproduction are reasons for cell division
chromosomes are key to cell’s survival
chromosomes are instructions for running cell processes
bacterial chromosome is circular
binary fission is splitting in half
eukaryotes have more chromosomes
mitochondria and chloroplasts divide by fission
regulate own division
some genes are in m and c
organelles break down during cd
nuclear env., ER, golgi
2 types in euks.-mitosis and meiosis
mitosis-2 daughters identical to parent
growth and repair in body cells
somatic cells
meiosis-4 daughter cells w/ half # of chromosomes
used exclusively for reproduction
cell division occurs in M
rest of cycle is interphase
mitosis-div. of nucleus
cytokinesis-M-div. of cytoplasm
gap=G
separate M phase from S phase
S phase-chromosomes replicated, involves DNA replication
G2-growth and prep for cd, chromosome are quality controlled
G1-growth and prep for cd
cancer=lack of reg. of cell cycle
cells can exit through G1 and enter G0-stopped dividing
3 ways freq depends on cell typefrequent, based on need, rare or never
mature neurons never divide
G0 applies to 2 and 3
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cells divide more in a baby
growth is essential part of cell cycle
genome-DNA is genome,
RNA is gen. from DNA
all genes in a complete set of chromosomes
24 chromosomes in complete se
chromatin-complex of DNA and proteins found in nucleus in interphase
histones are proteins in chromatin, Dna wrapped around them
cell division-chromosomes
chromosomes-discrete units of genomes
fibrous structure
chromosome part of chromatin
1 DNA is in a chromosome
humans have 46-diff. DNA molecules
2 DNAs in replicated chromosomes-sister chromatids
25,000 genes in genome
gen. mat.=sister chrom., replic. chrom., genes
cytoskeleton apportions chromosomes
mitosis is continuous
newt lung cells have 22 chromosomes, 46 for humans
microtubules come from centrosome
prophase-chromosomes begin to condense and move
to opposite end of cell
prometaphase-chromosomes complete condensation
centrosomes become poles of mitotic spindle,
envelope breaks down
microtubules attach to centromeres at kinetochores
nonkin. micro. cause cell to stretch
tubulin makes up spindle
metaphase-chrom. line up in middle of cell
chromosomes are under tension
anaphase-sister chromatids are sep.
telophase-chromosomes decondense, 2 nuc. env.s
reform
cytokinesis-division of cytoplasm, cleavage furrow
forms and cell splits
microfilaments form ring that is furrow
asexual-single parent produces offspring-identical to
parent and each other by mitosis
some multicellular can do it
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sexual-2 parents produce offspring
vary from parents
by meiosis
meiosis occurs in gonads, which produces gametes
ovary and testes, ova or sperm
halves number of chromosomes
fertilization restores original number
contents of nucleus is karyotype
homologous chromosomes are pairs carrying the
same genes
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same size, same centromere position
one of each pair comes from one of our parents,
other came from other parent
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sisters have identical DNA molecules
arise from DNA replication
nucleotide sequences can be slightly different
autosome-not directly involved in sex det.
humans have 44, 22 pairs
last pair is sex chromosomes
X and Y aren’t homologous
XX is homolog.
F-23 hp, M-22 hp
somatic cells-2n-diploid-paternal and maternal
diploid number is 46
gametes-haploid: n-one chrom. set
zygote-product of gametes: diploid
animals have prom. diploid and minor haploid phase
meiosis 1 sep. homol. chrom.
meiosis 2 sep. sister chrom.
result is 4 daughters, which have half number of
chrom.
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meiosis 2 is like mitosis, meiosis 1 is unique
DNA is replicated before meiosis
3 cell divisions in meiosis
unique events: homologous chromosomes pair,
resulting in tetrads
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chromatids overlap, which is chiasma
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chiasma is where crossing over occurs
chromatids are exchanged
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metaphase1-homol. pairs of chrom. align
anaphase 1-homologous pairs separate
telo 1-cells divide
meiosis 2 is same as mitosis
mitosis produces identical cells
3 gen. var.-indep. assortment, crossing over, random
fertilization
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metaphase 1 is lined up and has pairs
number of combinations=2n
n=2, so 4 comb.
humans=2^23=8 million poss.
chromomes are either maternal or paternal
crossing over between non-identical sister chromatids
ia gen. var. in 2 places
metaphase 2, no ident. sc
70 trillion poss.